Birds are a key part of “One Health”, acting as successful long-distance vectors and reservoirs for numerous zoonotic bacterial, parasitic and viral pathogens. One example of such avian “One Health” pathogens are species of the genus Chlamydia, including the well known C. psittaci. Presently, there is a lack of studies investigating C. psittaci and other chlamydial species in Australian birds and the risks they pose to humans and other animals. Recent studies also indicated that coinfection with the most significant psittacine virus in Australia, Beak and Feather Disease Virus (BFDV), is common.
We investigated the prevalence and genetic diversity of chlamydial organisms infecting wild birds from Queensland and coinfections with BFDV. We screened 1114 samples collected from 564 different birds from 16 orders admitted to the Australia Zoo Wildlife Hospital from May 2019 – February 2021 for Chlamydia and BFDV. Utilising species-specific qPCR assays, we revealed an overall Chlamydiaceae prevalence of 29.3% (165/564; CI 0.26 – 0.33) in tested birds, including 3.19% (18/564; CI 0.02 – 0.05) prevalence of the zoonotic C. psittaci. Chlamydiaceae coinfection with BFDV was detected in 9.8% (55/564; CI 0.08 – 0.12) birds. Molecular characterisation utilising the chlamydial 16S rRNA gene revealed that C. psittaci and novel genetically diverse Chlamydia species, such as avian C. abortus, C. ibidis and C. pneumoniae, were detected for the first time in Australia, infecting novel avian hosts (crows, figbirds, herons, kookaburras, lapwings and shearwaters) besides psittacine species.
This study provides evidence that C. psittaci and other emerging Chlamydia are prevalent in a wider range of avian hosts than previously anticipated. Globally, there is mounting evidence of the zoonotic potential of these avian emerging C. abortus and C. pneumoniae species, potentially increasing the risk of spillover to Australian wildlife, livestock and humans. Going forward, we need to further characterise C. psittaci and other emerging Chlamydia species to determine their exact genetic identity, potential reservoirs, and factors influencing infection spillover.